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X Prize launch
SpaceShipOne with pilot Brian Binnie rocket into space on the second of two flights needed to win the $10 million X Prize. (2min 32sec file)
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Monday's flight
This longer length clip of SpaceShipOne's second X Prize launch following the ascent, feathering of the wings and the start of re-entry. (5min 56sec file)
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Safe landing
Brian Binnie, the world's second private astronaut, brings SpaceShipOne to a safe landing at Mojave airport to capture the X Prize. (5min 55sec file)
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Launch of SpaceShipOne
Watch the hair-raising flight of SpaceShipOne during the first of two launches needed to win the $10 million X Prize. The craft experienced a major rolling motion and early engine shutdown. (3min 40sec file)
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X-43A test
NASA's X-43A research craft and its Pegasus rocket booster complete a captive carry test flight aboard a B-52 launch aircraft. (1min 48sec file)
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See the KSC damage
See damage to the Vehicle Assembly Building, the Saturn 5 Center and other facilities at Kennedy Space Center caused by Hurricane Jeanne. (4min 31sec file)
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Cape damage report
Jim Kennedy, director of the Kennedy Space Center, and Col. Mark Owen, 45th Space Wing commander, hold a news conference on Monday, Sept. 27 to provide a preliminary report on damage from Hurricane Jeanne at KSC and Cape Canaveral Air Force Station. (49min 30sec file)
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Hurricane Jeanne
Cameras aboard the International Space Station captured these views of Hurricane Jeanne on Saturday, Sept. 25 as the storm approached Florida. (3min 59sec file)
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Station news briefing
International Space Station program manager Bill Gerstenmaier holds a news conference Sept. 24 to discuss problems with the oxygen generation system and Expedition 10 launch preparations. (44min 06sec file)
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Galaxy clusters collide
Scientists describe a cosmic hurricane in this news conference from Sept. 23, explaining how two merging galaxy clusters churn high-pressure shock waves that leave thousands of galaxies strewn in the wake. (53min 24sec file)
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Station chat with kids
Expedition 9 commander Gennedy Padalka and flight engineer Mike Fincke talk about life aboard the International Space Station during an in-flight educational event with students at the Carnegie Science Center in Pittsburgh. (19min 00sec file)
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ISS educational event
The International Space Station's Expedition 9 crew hold an educational talk with students and members of the National Guard Bureau in Charleston, West Virginia. (19min 53sec file)
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Frequent starbursts sterilize center of Milky Way
Posted: October 5, 2004

Life near the center of our galaxy never had a chance. Every 20 million years on average, gas pours into the galactic center and slams together, creating millions of new stars. The more massive stars soon go supernova, exploding violently and blasting the surrounding space with enough energy to sterilize it completely. This scenario is detailed by astronomer Antony Stark (Harvard-Smithsonian Center for Astrophysics) and colleagues in the October 10, 2004, issue of The Astrophysical Journal Letters.

Say goodbye to the neighborhood! On this hypothetical world near the center of the Milky Way, the planet's sun paints the sky purple as descends toward the horizon at left. However, the bright supernova exploding at upper right lends an ominous feeling because its radiation is about to wipe out the alien life on this world. The galactic center is so dense with bright, hot stars that several can be seen through the cloudy twilight sky. Credit: David A. Aguilar, CfA
The team's discovery was made possible using the unique capabilities of the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO). It is the only observatory in the world able to make large-scale maps of the sky at submillimeter wavelengths.

The gas for each starburst comes from a ring of material located about 500 light-years from the center of our galaxy. Gas collects there under the influence of the galactic bar-a stretched oval of stars 6,000 light-years long rotating in the middle of the Milky Way. Tidal forces and interactions with this bar cause the ring of gas to build up to higher and higher densities until it reaches a critical density or "tipping point." At that point, the gas collapses down into the galactic center and smashes together, fueling a huge burst of star formation.

"A starburst is star formation gone wild," says Stark.

Astronomers see starbursts in many galaxies, most often colliding galaxies where lots of gas crashes together. But starbursts can happen in isolated galaxies too, including our own galaxy, the Milky Way.

The next starburst in the Milky Way is coming relatively soon, predicts Stark. "It likely will happen within the next 10 million years."

That assessment is based on the team's measurements showing that the gas density in the ring is nearing the critical density. Once that threshold is crossed, the ring will collapse and a starburst will blaze forth on an unimaginably huge scale.

Some 30 million solar masses of matter will flood inward, overwhelming the 3 million solar mass black hole at the galactic center. The black hole, massive as it is, will be unable to consume most of the gas.

"It would be like trying to fill a dog dish with a firehose," says Stark. Instead, most of the gas will form millions of new stars.

The more massive stars will burn their fuel quickly, exhausting it in only a few million years. Then, they will explode as supernovae and irradiate the surrounding space. With so many stars packed so close together as a result of the starburst, the entire galactic center will be impacted dramatically enough to kill any life on an Earth-like planet. Fortunately, the Earth itself lies about 25,000 light-years away, far enough that we are not in danger.

The facility used to make this discovery, AST/RO, is a 1.7-meter-diameter telescope that operates in one of the most challenging environments on the planet-the frigid desert of Antarctica. It is located at the National Science Foundation's Amundsen-Scott Station at the South Pole. The air at the South Pole is very dry and cold, so radiation that would be absorbed by water vapor at other sites can reach the ground and be detected.

"These observations have helped advance our understanding of star formation in the Milky Way," says Stark. "We hope to continue those advancements by collaborating with researchers who are working on the Spitzer Space Telescope's Legacy Science Program. AST/RO's complementary observations would uniquely contribute to that effort."

Stark's co-authors on the paper announcing this finding are Christopher L. Martin, Wilfred M. Walsh, Kecheng Xiao and Adair P. Lane (Harvard-Smithsonian Center for Astrophysics), and Christopher K. Walker (Steward Observatory).

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.